text:
Do airports commonly have mogas for sale on campus?
The ICON A5 POH gently implies, and other sources outright claim, that its Rotax 120iS prefers a diet of 87 octane mogas, and I've found a couple of sources claiming that while it'll take 100LL, the lead builds up in the oil, requiring more frequent oil changes.
The POH itself says that you should be mindful of vapour-lock, especially at higher altitudes or hot air temperatures. They suggest a blend of mogas and avgas is a good practice when in doubt.
Obviously if you've folded the wings and put your flying jetski on a trailer, you can probably top up the tank at any gas station, but as I'm preparing to simulate flying the Appalachian Trail, including a staging flight from Massachusetts to Georgia, it occurs to me that the trailer stays at home.
So when you're on tour, flying the thing airport to airport, if you want to use mogas.... where do you even get it? Do airport fuel stations commonly have mogas available? If so, how is it usually priced and can you tell which places would have it from sources like Skyvector?
Or is this a case of "bring a few jerry cans and expect to hike to and from the nearest gas station?"

What type of airports are you going to be flying into? Small, local fields with lots of ultralights and microlights are much more likely to have mogas on hand than if you fly into ORD.

Today I learned that lead has not yet been phased out of aviation fuel.

@GdD The full trip has me doing everything from Class C down to abandoned gravel strips in the middle of nowhere.

It hasn't been phased out of aviation gasoline yet @MichaelSeifert, but it is being worked on. Jet fuel has never had it.

www.pure-gas.org

In theory, flight planning tools will show you where mogas is available and the price. However, a quick look at SkyVector shows only 8 airports in the entire CONUS, and none of them are along your route from MA to GA. Most likely, the places that do have it simply aren’t uploading the data.
Fortunately, some folks have created their own maps, e.g. FlyUnleaded, that paint a much more encouraging picture. It just adds an extra step to your flight planning.
In general, you’re more likely to find mogas at smaller airports that have a large light-sport and ultralight presence. Anywhere big enough to carry jet fuel is unlikely to carry mogas too, simply because they don’t want the hassle of carrying too many fuel types.
It’s not all bad news, though. 100LL is pretty much a given if an airport carries fuel at all, and your ICON can use that when needed, even if it’s not ideal.

Honestly given the high-temp vapour-lock warning, for the lower half of the trail, and since the flight will be simmed for late-june/early july, I'd plan on never running with less than 50% avgas anyway until the OAT was regularly below 90F, so it's not a huge deal, but that link is pretty nifty, thank you!

If you're going to use gas from a service station, it'll have to be premium to be alcohol free, and even then you test it with the water/shake test to make sure there's no alcohol in it.  I use mogas in my Lyc powered homebuilt and did have problems with incipient vapour lock during really hot weather, and finally installed a cooling shroud on my engine fuel pump which seems to have fixed the problem.

@JohnK Since ethanol boosts octane, premium may have more than lower grades. It’s unwise to use gas from any auto filling station in a plane unless you can verify yourself that it’s truly ethanol-free.

@StephenS That's why I said do the water/shake test.  Normally premium is the only auto fuel without ethanol blended in, but you'd have to check anyway.  You CAN use mogas with ethanol if you are certain that all of the rubber components, hoses and seals, including the little rubber tip on the float valve in the carb, are compatible with it, which doesn't apply to most airplanes made with standard fuel system materials.

@JohnK The POH for the A5 specifically says automotive grade mogas with no more than 10% ethanol is a-okay, and lists it as the first fuel option, no less.

@ William Walker III you're good to go then.  Just make sure you use a quality brand from a station that sells lots, and that the fuel is summer grade (lower vapor pressure).  The lead is also incompatible with synthetic oil, so if the engine is using automotive oil don't use a full poly-alfa-olefin synthetic if running avgas for extended periods. PAO synthetics are not able to hold lead combustion products in suspension,as Mobil discovered after a few years of selling AV1 and a big class action suit.  I believe that Aeroshell Oil Sport Plus is a semi-synthetic and is ok with leaded avgas.

Been watching the TV series about Buffalo Airways, and they are saying they have to get away from their old piston planes because of the difficulty of finding avgas in the Canadian outback.  But apparently Jet A is readily available.  In one episode they loaded their DC-4 with barrels of avgas because they expected to find none locally.


text:
At what altitude will an explosive depressurization cause structural failure?
Rapid depressurization at high altitude is generally a very, very bad thing, because the aircraft will quickly loose altitude and may suffer damage to vital areas. There are three forms of depressurization: gradual depressurization, rapid depressurization, and explosive depressurization. As the name suggests, explosive depressurization is the most serious of all, and can cause various issues, ranging from minor damages like a blown-out door and someone sucked out (see Southwest Airlines Flight 1380), to complete structural failure and/or loss of control and subsequent crash (see Turkish Airlines Flight 981). However, my question is, at what altitude will an explosive depressurization cause structural failure? I reasoned that the higher the aircraft, the higher the pressure difference between the surrounding air and the inside of the aircraft before the depressurization, and thus the more severe the depressurization event. However, I may be wrong, so please tell me if my assumption is incorrect. My question can be summarized as follows:

Why do some explosive depressurization cause structural failure while others just cause minor damage?
is the above because of altitude (i.e., the higher the altitude, the more severe the damage.)?
if it is because of altitude, then at (approximately) what altitude will an explosive depressurization event cause structural failure?

I appreciate any explanation. Thanks in advance!

"because the aircraft will quickly loose altitude" -> that is a common misconception from Hollywood movies. The aircraft can maintain altitude after an explosive depressurization just fine (except when control cables are damaged, like in THY981). It's just bad for the people on board, so the pilots typically initiate an emergency descent.

the title makes no sense, altitude is orthogonal to the cause of structural failure.

I'm downvoting, because like your other questions, you make completely unfounded assertions.

@Bianfable Thanks for pointing out, so explosive depressurization does not cause a loss of altitude. It's just because of the emergency decent made by the pilots, which is part of the standard procedure of reacting to an explosive depressurization. Thanks, I learned something new here.

@Federico I'm not so sure if the altitude is connected with structural failure, and stated so in my post. So, if you think they are not related, you can tell me in comments (as you did), or post an answer stating that, rather than downvoting. Anyways, can you please suggest a title that you think makes more sense and better? Thanks!

@MichaelHall What assumption do you think is "completely unfounded"? Is it also the assumption of the higher the altitude, the more severe the damage thing?  Can you please state which assumption you think is incorrect so I can possibly change it? Also, you can just tell me that my assumption is incorrect and I'll change it, no need to downvote. Additionally, which of my other posts that you downvoted because of unfounded assumptions? Please tell me, so I can improve them as well. Thanks.

"Rapid depressurization at high altitude is generally a very, very bad thing, because the aircraft will quickly loose altitude and may suffer damage to vital areas." and "the slightest movement of an elephant that weighs more than 3 tons would most likely cause the aircraft to roll, pitch, or drop, and may even break the fuselage if the elephant's force is great enough." are the two statements that immediately come to mind.

I think you simply have to write your question without much more straightforward without much blah blah around it

@sophit Can you please explain a bit more? What does "without much more straightforward without much blah blah around it" mean? What parts do you think I can remove? Thanks :)

Oh, this question is unexpectedly extremely ill-received. Can anyone please tell me how to improve to make this post useful to future readers? Also, I can't delete this question now, and I would like to stop the downvoting. Are there any suggestions? What part(s) should I delete, what should I clarify more, and what should I reword/rephrase? I'll appreciate any help. Thanks a lot in advance!

You have it backwards:  Explosive decompression doesn't cause structural failure, structural failure causes explosive decompression.
The pressure differential is greater at high altitude which increases the probability and severity of such an event, but is otherwise irrelevant.

source: Stack Exchange

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

sort: votes


text:
How much priority is given to Air Force One?
Under normal circumstances (i.e., all normal aircraft), ATC priority is quite trivial: aircraft in distress and emergency situations goes first, then comes those who declared "fuel emergency", and then those who have already waited for a long time already, and finally, those who had just started waiting. This priority and precedence is all trivial and clear. However, when presidential aircraft comes into play, things get murkier. My question is, how exactly are incoming flights prioritized by ATC if one of them is Air Force One (or the name of the presidential aircraft in another country)? For example, will presidential aircraft get priority over aircraft who already waited a long time, aircraft who were diverted, aircraft who declared "fuel emergency", or even (hopefully not) aircraft who declared technical issues? I know full-blown emergencies ("mayday" or "pan-pan") still gets priority no matter what, but will those conditions listed above get priority or will Air Force One get priority? Can anyone (preferably ATCs) please provide some insights on this? I'll appreciate any help. Thanks in advance!

Just as a side note, priority is slightly less trivial than you imply. Where I work it's distress, urgency, ambulance flights, military flights expecting minimum fuel, control flights (i.e. ILS calibration), other flights (incl. scheduled air traffic) and finally sightseeing and school/training flights, except that school flights are prioritized the same as "other flights" when they are on a CAA-check (i.e. final check to obtain their license)

I would assume if there are enough other airplanes so close to AF1 that you have to worry about "priorities", something has gone horribly wrong already.

I don’t know if there are specific procedures, it is probably arrenged on national level when AF1 is expected for a visit. I once operated to an airport where AF1 was departing and basically the entire international airport was closed when the AF1 was moving. All the departing traffic waited at the gate and all the arriving traffic was in holding pattern until the thing got airborne.

Any comments from downvoters?

@60levelchange Thanks for pointing out, my list of "normal" situations is not complete. Do you suggest me to add those conditions to my list as well?

@JörgWMittag I don't think ATC would have the time and space to clear the whole airspace near where Air Force One is flying. There must always be other aircraft waiting in line behind the presidential aircraft.

Note: it depends: you wrote also about the equivalent in other countries, but it depends within the country or outside. Military aviation has own priorities (and procedures). Head of states (in foreign countries) have some security guarantee, by Vienna (so not direct on aviation, but for security reason, it may be better to have priority to leave airport quickly (the person, not the aircraft), so to reduce security and block inside apron area. Very generic and probably part of protocol, so parties will agree before a travel (which requires authorization anyway, still bc Vienna).

Why the aggressive downvoting? Can anyone please explain why this is such a bad question? I hope to make this useful to future readers, so I wish to improve my question. I'll appreciate any suggestions or direct edits. Thanks in advance!

The AIM discusses “aircraft in distress” as having ultimate priority, then “air ambulance”, then says the following about Air Force One (and similar):

Provide priority handling and expedite the movement of presidential aircraft and entourage

Priorities discussed after this are search and rescue and air intercept.
That’s it. What is distress? I’d guess it doesn’t include “aircraft that have waited a long time”.
Of course, the Secret Service is in the room with the controllers during a presidential visit, so questions about relative priority can be addressed on the spot.

Thanks for your answer! It is very helpful and informative, I learned from it. Please take my upvote as a token of my gratitude. I'm looking for more specific precedence and priority protocol given to ATC, though. Preferably a list. Still, thanks for your answer!

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/


text:
Had there ever been an accident caused by chatting in the cockpit?
Almost all large commercial jet airliners today have at least a captain and a first officer as the flight crew. Some cargo aircraft or old airliners also have a flight engineer. Additionally, most long hauled flights have an additional relief captain or even a complete relief flight crew. According to aircraft regulations, pilots should focus on their work and not small talk when in crucial stages of the flight, i.e. taxing, take-off, climb, decent, approach, and landing. In the cruise phase, especially if the flight is a long-haul, the autopilot basically flies the plane on the intended route, and pilots are allowed to chat a little while still monitoring the flight of the aircraft and reacting to any anomalies that may happen. However, my question is, had there ever been a case where pilots broke this rule and chat in the crucial phases, and as a result caused an accident? After all, some pilots are extremely experienced, so they might've thought that they can chat while also performing their duties. Reality is, no matter how experienced a pilot can be, if they don't focus on their work, there's a large chance that there'll be a crash. So, had there ever been a crash caused by chatting in the cockpit in crucial phases of the flight? Or did every pilot adhered to the rules and focusing solely on their work when in the crucial stages? Or are some pilots actually experienced enough to fly the planes while doing other things? I appreciate any experience form pilots or any insights into this. Thanks in advance!

There have been incidents where things went off the rails where chit chat distractions were a major factor, usually on arrivals and approaches, although I can't think of specifics. In any case, the rule followed throughout the industry for many years is no small talk below 10,000 ft, coming or going. In western airline operations this is generally enforced. In dev world operations, maybe less so.

This may be trick to answer wiki page https://en.wikipedia.org/wiki/Sterile_flight_deck_rule appears to include a list of related incidents but would expect there to be few if any incidents where 'chatting' outright caused an incident, rather where it lead to something critical being missed

@AircraftEnthusiast007 I suspect this got some down votes for asking this question while simultaneously saying that 'there is a large chance there will be a crash' if pilots chat. This can be read that you are either asking this question in bad faith, or honestly believe pilots too dumb to talk and fly at the same time. From your other questions suspect that is not the case, but is how this question looks in isolation. Anytime you want an subject expert to answer, try to avoid anything that throws shade at that expert.

OK, thanks for the suggestion, so do I just delete that sentence? I certainly do not have any disrespect or distrust of pilots in anyway, and if my post shows this I apologize. Again, this is absolutely not what I mean and I would like to change that. So, do you suggest I just delete the sentence, or somehow reword it? If the latter, can you please give some advice on how to express what I actually mean while not sounding offensive? I appreciate your explanation and would like to hear your thoughts. Thanks :)

From the downvote tooltip: "This question does not show any research effort"

As for downvoting: I agree with @nobody since the answer to this question is readily availlable by simply googling and visiting the wikipedia article from the top of the search results. The reason for the "sterile cocpit rule" are the many accidents in which focus of the pilots was disturbed by chatting during critical phases of flight.

Air accidents rarely only have a single cause, but rather a list of contributing factors. Out of the top hundred accidents, distraction from conversation has been a contributing factor in some, but not the only one.
Chatter in the cockpit is more often a symptom of fatigue than the beginning of the accident chain of events. People intuitively try to stay awake and partially alert by engaging in conversation. It can also be a sign of complacency, which is more common in general aviation.
A major 2022 study has attempted to quantify the effect of various human factors on errors. Conversations are grouped under "Distraction from external factors". It was based on cabin crew rather than cockpit, but I haven't seen a study that specifically addresses pilot conversations.
Study on Factors That Influence Human Errors: Focused on Cabin Crew

The conclusion of the study did not support the hypothesis that conversations lead to a meaningfully higher human error rate. To clarify the numbers, β is the adjusted correlation coefficient, and p is the probability to see a positive correlation from random data. While science rarely closes the door on any hypothesis, a p-value above 0.5 means it's more likely wrong than right.
In other words, carrying out conversations does not, by itself, cause more errors, neither does time pressure. In contrast, fatigue, psychological stress and complacency definitely do.
Our brains have some capacity to filter out distractions and snap back to important tasks once alerted. This requires the higher-order cognitive system (also known as system 2), which gets severely degraded by fatigue or stress. There's also different grades of distraction, with a clicky pen or a fidget spinner on the lower end and a VR headset on the upper.
The Northwest 188 incident (thanks Aadiraj) was caused by distraction. However, it was much more severe than just conversations. Both pilots took off their headsets, took out their laptops, and worked the scheduling system together. This is much closer to VR than to idle chatter - the pilots were absorbed by a complex IT system, which required complete focus. The plane was a distraction, which their brains had successfully filtered out.
The sterile cockpit rule does allow for higher crew alertness and engagement, which help prevent other issues from developing into an accident. But other factors matter more.

Thanks a lot for your answer, it is very helpful. So chatting had never been the main reason of an accident. Your explanation is very clear and informative, so thanks for the great answer! Upvoted your post to show my gratitude :)

@AircraftEnthusiast007 I wouldn't say we know that, but if it was, we have no confirmation of that. For other factors, we have ample proof.

Northwest Airlines Flight 188 maybe?? Why not?

@AadirajAnil Maybe. However, the pilots' fault was far worse than idle chatter: they were both focused on another task, even working with a laptop. That's akin to doing a remote coding job.

@AircraftEnthusiast007 and others in this comment section: if not adhering to sterile cocpit rule was considered a factor, it shoud be seen as a partial reason for the accident. To put it otherwise: if the pilots had paid appropriate attention to their duties, they could have managed the other factors properly. So it is safe to say chatting has been a reason for many crashes.

There's grades of distraction, between small talk and escaping into a virtual reality. The Northwest case is much closer to the latter - the pilots were absorbed by a complex IT system that required complete focus. The plane was a distraction they successfully filtered out.

@Therac, by the time the captain figured out how to use the system, he didn't need it anymore.

@AadirajAnil Work-related distractions are the worst. At least, if you're playing video games at work, there's a trigger in the back of your mind to look out for the boss. Needless meetings look and feel like work, removing that alertness. So does working the company's scheduling system.

Not exactly conversation, but the infamous Eastern flight 401 that crashed while the crew was trying to change a light bulb on a landing gear indicator.  everyone was concentrating on how to change the bulb and no one was actually flying the plane. It was on autopilot, but someone, possibly the pilot, lean against the control wheel which disconnected the autopilot.  this was before the ground proximity warning systems which are now required due to this accident.

@AircraftEnthusiast007 Are you familiar with the swiss cheese model of accidents? The whole idea is that an accident almost never has a single cause. An incident usually is caused by a series of mistakes and failures that stack up in just the right way to avoid all the preventative measures. It's valid to say that distractions during a critical phase of flight have been major contributors to accidents in the past, but distraction alone almost never causes an incident; it's a distraction that lets a failure go unnoticed and grow from a simple "oops" to a life threatening situation.

@DarthPseudonym I agree that most accidents have multiple causes, but here I'm asking about something routine that was forgotten by pilots due to distractions. By "routine", I mean like they forgot to extend the landing gear, flaps, forgot to flare or rotate, or something similar. So I guess you can call what I want as having only one cause.

I don't think there's anything like that. There have been cases where an airliner accidentally landed with the the gear up, but not because Talk Too Much. Those routines are so routine that it would be hard to miss a step unless you have something going wrong that causes task saturation -- like, something disrupts the usual flow of the landing process, the pilot refuses to go around (get-there-itis) and in all the chaos a critical step gets skipped over. But that's not for chitty-chat reasons, it's usually like a plane-threatening situation came up at a bad moment.


text:
Are stories of autopilots in things like the J-3 basically urban myth?
While my own research makes plain that the Cub-owning community seems to consider the idea of installing even the most basic autopilot into a Cub a mortal sin, there are scattered accounts on the web of J-3 owners operating with installed autopilots (mostly for long-distance cross country flying).
But as I tried to determine what such a modification would cost, I quickly discovered that autopilots are expressly, explicitly, and strictly the realm of STCs (emhpasis added):

D.13h -
Autopilots (AP), Flight Guidance Systems, and automatic flight
control systems (AFCS) or flight directors (FD) -
STC

Meaning that nothing less than a pre-existing Supplemental Type Certificate would make such an installation legal.  Since STCs are pursued by the aircraft manufacturers (or the 3rd party vendor who wants to open the market for their product), I presume the costs of such are prohibitive (millions of dollars).
Are the folks claiming to have such equipment making it up? If not, how did they get around the lack of any existing autopilot-related STC for the J3?

The lack of an electrical system is a teeny tiny impediment for a J-3.  But assuming you had an electrical system, there's nothing really stopping you except mental health laws against developing insane and pointless ideas.

Part 43 (https://www.law.cornell.edu/cfr/text/14/appendix-A_to_part_43) seems to strongly disagree?

The autopilot was invented in 1912, so it is possible a few got "grandfathered" in for cross country, perhaps for one person and a lot of additional fuel.

No nothing to stop you if the airplane has an electrical system and you want to go to all the trouble. Only a crazy person would though. which was my point.  And the J-3 doesn't have, you know, an electrical system.

@JohnK I must completely misunderstand the whole point of Supplemental Type Certificates then, and regulations regarding major modifications to aircraft. Adding an electrical system (its own major modification) doesn't seem any harder than adding the autopilot itself. So if there's something I'm fundamentally missing about the law here, I'd love to have that clarified and would accept that as an answer.

@WilliamWalkerIII you could create an STC to add an electrical system to the J-3, using say a belt driven alternator (the A-65 has no provision for a generator) voltage regulator, contactors, wiring, all that.  Then you could do another STC to add some kind of autopilot to work the flight controls, although you would have to add gyro instruments and radios, etc, and there is no place to put all that stuff.  My main point is you would never even start such a project on a J3 Cub.  It'd be like adding an air conditioning system to a golf cart.

Didn’t someone make some kind of demented strap-on yoke mounted autopilot for 172s a while back. Would something like that be ok?

Early Piper Cubs had no electrical system so an autopilot install, forgetting about certs for a minute, was simply not possible for a good chunk of the aircraft's history. But a lot has changed since the cubs first rolled out of Lock Haven over 80 years ago and electrical systems have been added to some aircraft.
Its been added successfully (it seems) to some Super Cubs and there are lots of aircraft that now fall under the "Cub" header.
If you are talking strictly about the early J3 Cubs which barely have the useful load for two modern sized adults, then adding an electrical system, servos, and the required avionics becomes a practical issue at some point. The new glass units that can drive autopilots make this more feasible.
I think it ultimately comes down to a limited use case and little drive for getting one certified by any major manufacturer. Most of the Cub owners I know are either flying low and slow, doing aerobatics (in some Cub variant), landing on river banks or mountain tops, or towing banners on clear days. These are not really autopilot-required situations as they are basically all VFR flying and some sort of special case at that. While I'm not saying you can't use an autopilot to fly VFR the real value (for the flying I do regularly) is a fully coupled IFR approach in hard IMC down to minimums, or reducing work load on a long XC flight, neither of which I really see people doing in Cubs. Again this may just be the Cub owners I have encountered, and with a top speed of ~83MPH in a J3 you may as well drive these days...
The companies that sink time and money into building certified units likely also have this view and the numbers just don't drive the certification of a unit for an aircraft no one will install it in and an airframe that may not even be able to support it in the first place.
So, urban myth, maybe, statistically unlikely, I think so.

"Its been added successfully (it seems) to some Super Cubs and there are lots of aircraft that now fall under the "Cub" header." This is probably where I'm running into confusion, the word 'Cub' has lost its meaning in a lot of ways.

I cannot say whether autopilots on J3 cubs are a real thing or not, but it is possible from a regulatory point of view because you only need an STC if you want your airplane to have a type certificate. If you make a modification which would require an STC where none exists then you invalidate your type certificate and your aircraft is unairworthy. You have two choices then (this is for FAA), you can remove the modification and make it conform to the standard, or you can apply for a special airworthiness certificate, making it an experimental aircraft.
An experimental category aircraft will be issued a special airworthiness certificate and still be flown, albeit with limitations, i.e. only day VFR over non-built-up areas. To get that certificate the airplane must be shown to be safe with the modifications. So, you can do all manner of weird stuff as long as it's not going to kill you or anyone else without having an STC. Regulations differ across the world but most regulations I've seen have a similar structure. For example in the UK you would look to fly it under a Certificate of Airworthiness (CofA).
STCs cost a great deal of money because of all of the testing that has to be done to obtain them, so there has to be a compelling finance case to be worth it. Not enough people would want or be able to pay for an autopilot on a J3 for it to make money, so there's no STC for it. This is likely because the cub is one of the worst possible options for long cross country flights due to its slow speed.  However, there's nothing stopping you from doing it as long as it could be done safely.

Both you, and some commenters, have made it sound like STCs are things that people can just do? The people who purportedly fly these things with APs and radios, don't exactly strike me as 1%ers so where could the millions of dollars in prototyping/engineering have come from in those cases?

What I'm saying is that you don't need an STC for an experimental airplane @WilliamWalkerIII. While an individual could theoretically develop a STC, typically that would be a manufacturer.

@GbD Okay.  The experimental status is interesting. How densely populated can you get away with? I'm not planning on buying a J-3, but I am planning on flying LSAs and experimental stuff seems to be restricted in the same ways... except I live in the Boston area, lots of B and C airspace, which is obviously out, but can I fly out of class D?

You can fly in any class of airspace with an experimental airplane as long as it has the equipment required for that airspace. Why don't you read up on Part 91.319 of FAR/AIM.


text:
What is the correct terminology for the ICON A5's wing configuration?
The ICON A5 would seem to be a "conventional" (if we stretch the limits of the term) high-wing monoplane.
But what about these things right here:
The protrusions from the hull, circled in red, are called "Seawings(tm)."  Their declared purpose, according to the POH, is to stabilize the aircraft in water as well as provide pilot and passenger with a means of convenient in- and egress from the cockpit.
I can't find any confirmation or denial as to whether or not they generate any kind of lift, but they do seem to be shaped in a way that could be a manner of airfoil - and certainly if you're designing an aircraft and have lateral protrusions from the hull and you don't shape them to produce lift you've missed an opportunity.
So for the moment, if we assume they do generate some modicum of lift, does that mean the ICON is no longer properly referred to as a monoplane?
My understanding is that "Biplane" would require the wings to be vertically stacked with each other.  Some small portion of the seawings does underlie the main wings, but the vast majority of the seawings' structure is well forward of the main wing.
Would that make it a Tandem-Wing aircraft?
Do either of those terms stop having meaning if the seawings - which are declared as intended to provide stability in water and footing for embarking/disembarking occupants - are instead properly though of as structurally part of the hull - and thus the aircraft is at least partially a lifting body?

It's not a tandem because both "wings" are at roughly the same position lengthwise. The term "sesquiplane" (one and a half wings, so somewhere between monoplane and biplane) exists, but I had never heard of it before googling it just now. But since I'm not sure that is the correct term (if a correct or well-established one even exists), I leave this as a comment and not an answer.

@Raketenolli If you mean the wings are at the same position front-to-rear, they're not. The seawings trailing edge is below the leading edge of the main wings, but the vast bulk of the seawings exists well forward of the main wing. (They wouldn't make good steps otherwise.)

"if you're designing an aircraft and have lateral protrusions from the hull and you don't shape them to produce lift you've missed an opportunity."  Brilliant phrasing!

A famous aircraft with similar "sponsons" (that's what they are normally called) to keep the plane level in the water is the Boeing 314 Clipper. "Sponsons" were also used (and likely originally pioneered) on Dornier flying boats. Examples include the Dornier Wal, Dornier Do X, and Dornier Do 24.
Re a comment: The term "sesquiplane" is normally applied to an airplane with a much larger lower "wing" than we see on the Icon A5-- such as the Nieuport 11.
Consider: should we call the Fokker Dr.1 a "quadruplane", because of the little "wing" on the axle?  (No, we should not.)
It would be a stretch to call the Icon A5, or the Boeing 314, or the Dornier flying boats noted above, anything other than high-wing monoplanes.

Ah - brief, correct and to the point. +1

@PeterKämpf -- "for once" ?  !! : )

Lift from a sponson should be avoided because the long chord but short span will give it a terrible lift/drag ratio, and if more lift is really needed, it is far better to add a little to the span. The higher the aspect ratio of a wing, the more efficient it is aerodynamically - and a sponson is about as low as it is possible to go in both respects. This is also the reason the lifting fuselage aircraft ended up less efficient than conventional aircraft.
They also don't work terribly well to balance the airplane while moving on the water, as dipping a wingtip was a common problem on all of the airplanes that used them, so much so that the wing tips had to be specially sealed to prevent them taking on water, and to ensure they were sufficiently buoyant, and preventable accidents have happened when a tip was dipped at speed. That said, when moored, the aircraft is more stable when level than a conventional hull for loading, and there is no tip float to cause problems when coming alongside a dock, while adding a convenient step.
As for the original question, I have never seen a case where a sponson was regarded as a wing, such as to upgrade a monoplane to a sesquiplane, however, unlike with the Fokker Dr.I, Nieuport monoplanes with extra large airfoils between the undercarriage were described as and named Sesquiplanes, so there might seem to be some precedent to do so, however the lift generated from a sponson is usually minimal, and the one case where the sponson was extended out to form a full sized wing was a failure because any deviation from perfectly level resulted in substantially more drag from the immersed wing.
Here is a photo of a Boeing 314 Clipper prototype dipping a wingtip at speed.


text:
Can the cabin crew enter the cockpit without asking the pilots to specifically allow them in?
The cabin crew serve not only passengers but also the pilots. They are also (presumably) trustworthy employees that have a very low chance of having malicious intent. Since calling the pilots and asking for them to unlock the cockpit door every time the cabin crew  comes to serve a meal or drink is pretty inconvenient, can they enter the cockpit without the explicit immediate approval of the pilots? Such as having the enter passcode or something similar. Or is there too much of a safety concern by doing so? What is the current situation? Also, if they have anything to report and can't reach the pilots by phone, can they go into the cockpit to check what's happening?

Yeah, it is inconvenient.  Security procedures usually are!

If it was possible to enter the cockpit without the pilots authorising it, neither Germanwings Flight 9525 nor (presumably) MH370 would have ended the way they did. The reaction to the former is that in most cases, a pilot is not allowed to remain in the cockpit alone: when one of them needs to exit, a cabin crew member will remain in the cockpit in the meantime, or some equivalent procedure.

@jcaron You can read the links on your article, it is possible to open the Germanwings A320 flight deck door without pilots authorizing it. It's just the pilots have a means to block to that access: there's an override to the override. See the answer below.

Any comments from downvoter?

In general, the cabin crew cannot access the flight deck of a passenger airliner without the pilot's explicit action to open the door. Normal procedure is to call the flight deck and ask for entry. There is also an emergency system with a secret code to allow access to the flight deck in case of pilot incapacitation, but the system still allows the pilots to reject entry. This is necessary in case of a hostage situation where cabin crew might be forced to enter this code.
For example, on the Boeing 777 the system works like this:

1 Keypad
Push - enters 3 to 8 digit emergency access code by pressing numeric then "ENT"
keys. Entry of correct emergency access code sounds flight deck chime.
2 Access Lights
Illuminated (red) - door locked or Flight Deck Access System switch OFF.
Illuminated (amber) - correct emergency access code entered.
Illuminated (green) - door unlocked.
[...]
The emergency access code is used to gain access to the flight deck in case of pilot
incapacitation. Annunciation of a flight deck chime and illumination of the amber
AUTO UNLK light indicates the correct emergency access code has been entered
and the door is programmed to unlock after a time delay. Selecting the DENY
position on the door lock selector denies entry and prevents further keypad entry
for several minutes. To allow entry, the selector is turned to the UNLKD position
which unlocks the door while held in that position. If the emergency access code
is entered and the pilot takes no action, the door unlocks after expiration of the
time delay. Before the door unlocks, the chime sounds continuously and the
AUTO UNLK light flashes.
By pressing "1" then "ENT" keys on the emergency access panel, the flight deck
chime will sound (if programmed).

(Boeing 777 FCOMv2 1.30 - Airplane General, Emergency Equipment, Doors, Windows: Flight Deck Emergency Access Panel)


text:
My ceiling fan preference is to have 5 blades because it's quieter. Do helicopters ever have 5 rotor blades. Why?
My home ceiling fans have 5 blades to reduce the wopwop sound in a quiet room.  It probably also moves air more efficiently at a lower spin rate.    Can a helicopter operate properly with 5 blades?

Related: Why are three-bladed helicopters relatively rare? and How to calculate the number of blades?

Compare and contrast a fan on the ceiling, a helicopter rotor and a turbofan for a jet engine. They all move air from one place to another.

This is not an attempt at an answer, but I have seen a five-bladed fan on a diesel engine which had asymmetric blades in order to reduce noise.

@MarkMorganLloyd, this is common.  It spreads the noise over a broader range of frequencies.  https://mechanics.stackexchange.com/questions/24327/why-are-the-blades-of-car-radiator-fans-unevenly-spaced

The most popular helicopter in the world has 5 blades. It's rare in the US, but elsewhere it's like the 737 of rotorcraft. Altogether, 5-blade designs account for about half of all helicopters outside of North America.
Odd vs even blade count doesn't matter much for ceiling fans. The slower the fastest point of the blade is, the quieter the fan. More blades allow for a slower rotation speed for given diameter. Also, if the diameter is decreased, the peak noise frequency moves up, with some extreme examples.
Odd blade counts are very common for Russian and European helicopters, as they make the noise quieter and less distinctive. The canceled Comanche "stealth helicopter" also used 5. Multi-blade rotors, especially with odd blade counts, are much more difficult to balance than simple 2-blade teetering rotors. However, once you get above 4 blades, it's a full balancing job anyway. Sikorsky easily switched from 6 to 7 blades in the CH-53E, and so did Mil from 5 in the Mi-6 to 8 in the Mi-26.
Even blade counts are more common in the US for historic reasons. While Sikorsky went with 3 blades from the start, as did Mil, but Bell, who preferred a simple 2-blade rotor, captured the market first. The Huey's success reinforced this. So 2 or 4 blades are seen as more conservative, even though the Apache's 4-blade rotor is as complex as any 3- or 5-blade one (it has dual teetering tail rotors though). American heavy-lift helicopters do use 5-7 blades.
For low-cost GA helicopters, there's no choice but a 2-blade teetering rotor - articulated hubs are too complex for that market.

I can almost imagine, though I may be wrong, that if you add enough blades it actually becomes easier to balance - though "enough" might a silly amount for a helicopter. After all, balancing a disk (such as a car wheel) is pretty trivial.

@GrimmTheOpiner A car wheel doesn't rotate fast enough to affect its structural integrity. Rotors and turbine disks do, and balancing turbines is quite difficult. So I'd say the challenge increase slows down after 5 blades, but doesn't drop.

Is it odd blade counts that make things quieter, or just more blades? Would 6 blades be quieter than 4? Could you fairly easily balance 6 blades (3 teetering blades)?

@JaminGrey For a household fan, more blades. For a helicopter rotor, where blades are approaching Mach 1, odd number or uneven angle between the blades. As for balancing, the Apache has 2x2 teetering blades on its tail rotor, but its main rotor has 4 separate blades, requiring a full balance job, made only slightly easier by their orthogonality.

@GrimmTheOpiner: Your mind is taking you towards the balanced centrifuge problem, but this is slightly different in that it assumes that a centrifuge has predetermined equidistant holes before you knew the amount of tubes you'd want to slot into it. Helicopter rotors are built with the explicitly knowledge of how many blades they will have, and so you can use any number of blades as long as they're equidistant (equiangular?) and it will be a balanced system. The only thing you can't do is build a one-bladed helicoper.

@GrimmTheOpiner It definitely gets easier to balance going from one blade to two.

Mi-8 ... who knew ?!

Airbus H145 is a 5 bladed helicopter, recently certified by the FAA and EASA. https://www.airbus.com/en/newsroom/press-releases/2020-06-five-bladed-h145-receives-type-certification-by-easa
And there are 6,7, even 8 bladed helicopters.

Does that high a blade count not massively reduce the efficiency by putting each blade closer to the next blade's turbulence?

@Sneftel Yes and no. The rotor need enough wing area and airspeed for lift. Wide-chord blades create a lot of induced drag. Extremely long blades are heavy and flex excessively. For large helicopters, more rotors is the best solution, more blades the much cheaper second-best.

Most H145s and predecessors are 4-bladed though.

@M2FKXY the switch to 5 blade was for the H145 a necessity due to the need to increase the mtow further (and to improve noise and performance in general). There were no more room for improvement with the old 4 blades design. The 5 blades rotor derives from the bluecopter platform.

Thanks a million. Went for an answer, stayed for an education!


text:
Is an eclipse considered 'night' for regulatory purposes?
A partial or total eclipse is as dark as twilight, but only for a short period. Does it count as night flying for regulatory purposes?
I'm looking for a UK answer, but information about the US is interesting too.

You are overestimating how dark it gets in an eclipse. sure, if you're flying straight through the umbra, it's quite dark, but that's at most 260 km wide. Even a cessna flies through that in less than an hour, not even taking into account that the umbra itself also moves. The penumbra, the area around it, is only as dark as twilight while the eclipse is well over 90% coverage. outside of that small area, you'd be struggling to even notice the eclipse.

@NateKerkhofs You are underestimating how recent my experience of an eclipse is. I wouldn't really expect it to count as a night flight in a log book, but I could believe it might activate LVP or some safety rules that normally only apply at night.

@Nzall:  A typical solar eclipse "moves" at roughly Mach 2. (https://sunearthday.nasa.gov/2006/faq.php), and is usually over in 2-3 minutes.  The speed of a Cessna is not even relevant.

No: that does not count as night flying.

The CAA defines "Night" (Air Navigation Order, Article 129) as:

‘Night’ means the time from half an hour after sunset until half an hour before sunrise (both times inclusive), sunset and sunrise being determined at surface level;

Similarly, the FAA's definition (FAR 1.1) is:

The time between the end of evening civil twilight and the beginning of morning civil twilight, as published in the American Air Almanac, converted to local time.

Since an eclipse is neither a sunset or sunrise, nor does it happen between evenings and mornings, it does not fit the definition of "Night" for legal purposes.

More definitions of night flying used by the FAA: http://www.aopa.org/News-and-Video/All-News/2005/October/11/Night-flying-Sort-through-the-different-definitions-of-night

This. However this is a neat place to note the difference between "rules" and "prudence". Obviously if you are going to fly (or more importantly, LAND) during the depths of an eclipse it would behoove you to consider all the elements that go into a successful night flight. Seems like an ultra-rare situation but if you're doing it on purpose, do it right! Remember you can always ask the tower to turn on the runway lights or some fields automate them with radio clicks - see your airport guide.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/


text:
Why don't we use elevator trim as the primary flight control?
One thing you're repeatedly told as a student pilot is to fly with the stick (or yoke), not the trimmer. To select a new pitch attitude, fly to it with the stick, wait for the aircraft to settle, and then trim away constant forces.
But the position of the elevator trimmer is roughly the same for the same cruise configuration. It would be a lot easier to mark the trimmer with "level flight at 80", "gliding descent", and "best climb" positions, and just move it to those positions (before or after setting the throttle appropriately) directly. The trimmer would be the primary means of setting attitude, with the front-back axis of the stick or yoke for temporary adjustments (e.g to bring the nose up a little in a turn).
So why aren't controls designed to be used that way, and why do we fly with the stick?

For every trim position there is a correlation between airspeed and center of gravity.  For any small slice of time, the CG will not change and so the trim position is only a function of airspeed.  If you mark the trim as you want, it won't be accurate for every CG position.

Proper trim control technique involves exerting control pressure to attain the desired attitude then using the trim to alleviate the requirement of holding that pressure. There can be a temptation for pilots to make small adjustments using trim alone. Resist the temptation and use the proper procedure.
We use the proper technique because it's the most precise way to use trim. If adjustments are made with the trim directly we'll end up over-controlling and chasing the correct trim position.
Trim isn't just a convenience. Especially for pilots flying in instrument conditions, alleviating the load of holding control pressure and ensuring that if the pilot lets go of the controls the airplane maintains its attitude are a matter of safety.
The Airplane Flying Handbook explains Trim Control starting on 3-6. It lists the proper technique in greater detail and provides a complete rationale.
There's also the matter of doing things the same way every time. Once we've established the right procedure, we should always use it to enforce the habit. This also benefits the pilot when things get busy. Proficient instrument pilots are experts in using trim effectively.
Predefined trim positions are impractical because they vary based on weight, CG, airspeed and other factors. These factors change the amount of downforce required on the elevator and therefore the trim position. Situations like "level at 8000" or "gliding descent" won't always result in the same trim position. For other control surfaces there are similar factors. We do have predefined trim positions for takeoff, but loading often makes those undesirable and trimming is required immediately.
During flight training, good trimming technique becomes especially important during instrument training. There's a lot of good information about trim and its importance in the Instrument Flying Handbook.

Great explanation, As a non-pilot, I was just wondering, with modern large and advanced aircraft, airliners and so on, is trim more automated?  So, once you're in a "position" you want, can you just press "trim me to here" and it figures how much trim to apply?  cheers

@JoeBlow Airbus are auto trimmed. When you release the stick it always stay where it was. Boeing 777 also has some kind of auto-trim: the computer will trim for a target speed and adjust for flaps and thrust changes.

Kev -- fascinating stuff.

Your answer puts a lot of effort into explaining the procedure and why procedures are important. That's somewhat tangential to the question. I feel like the 6th paragraph is the only thing relevant to what I actually asked.

I felt like I was answering the question "Why don't we use elevator trim as the primary flight control?"

@DanHulme The second paragraph was also quite important. You can achieve the attitude you want much more quickly and precisely by using the elevators/stabilators than you could be trimming, waiting for effect, trimming some more, waiting for effect, etc. You'll get the correct trim setting much faster and with less deviation from your altitude/airspeed by flying with the stick and throttle and then trimming to relieve stick pressure.

The main reason for having trim is to modify the forces felt by the pilot to relieve strain, or as you say, 'trim away' the constant forces.
There are various reason for not using the trim as the primary control or have fixed trim positions:

The forces on the stick and by extension the trim varies with the weight and balance of the aircraft. Though the position of the trim may be roughly same for same configuration, what if the configuration changes? What will happen if the number of passengers or luggage changes? By extension, as the fuel is consumed and the aircraft balance changes, the trim position changes. So you cannot have a fixed trim setting.
The trim position will change depending on whether the wing configuration is different for e.g if the flaps are extended.
The trim setting is affected by speed variations. For example, in trimmed condition, if the speed of aircraft is reduced, the stick will push the pilot's hand forward to lower the aircraft angle of attack. This is opposite of the requirement- we need higher angle of attack to maintain level flight at lower speed. The opposite happens as the aircraft is accelerated. This means that adjustment has to be made to trim,and the pilot will end up making more or less continuous adjustments to the trim.

The trim will behave differently with different loads, so you cannot use fixed trim settings on each flight, as each flight will be different from a load factor and center of gravity perspective.
While my trim setting for a solo flight with half full tanks will make me us best climb, the same trim setting with 3 additional passengers and full tanks will produce a different result. (Speaking from a GA/SEP perspective).

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/


text:
What if traffic should give way to me but doesn't appear to be?
Let's say I'm flying a GA aircraft VFR, and I don't have TCAS or similar. I see another aircraft on a converging course, and it must give way to me. (Suppose it has me on its right.) It doesn't appear to be changing course to avoid, so what should I do?
Obviously I shouldn't just wait for us to collide, but at the same time, I don't want to take action that will negate its avoiding action. (e.g. If I climb to avoid, and he climbs to avoid because he was expecting me to hold course, we will both still collide.)
The question seems to relate mostly to uncontrolled airspace, but I'd appreciate an answer that also covers controlled airspace possibilities.

Having read Keith S and Pondlife's answers, is there any point at which getting on the radio to communicate your presence and intended action useful?

@FreeMan In the situation which motivated the question (which isn't quite as the question describes), there wouldn't have been time to communicate before acting, so I was imagining immediate action is required in the question case. But an answer that includes radio as a suggestion will be appreciated too. "What should I do?" doesn't just mean manoeuvres.

Being able to communicate on the radio is predicated on you being on the same frequency as the "intruder". If you're in contact with ATC you might advise them of the TCAS alert and request instruction; if anyone's already in contact with the plane, they are. However, a VFR XC flight doesn't have to talk to anyone as long as they stay in E or G space. Theoretically he should be monitoring GUARD for emergency transmissions but that's not a guarantee either. Basically if your TCAS has alerted, you will likely collide before you raise the other pilot.

Whether you have the ROW or not, it is your responsibility to "see and avoid" even if the other pilot isn't. This is the aviation analog to defensive driving; call it "defensive flying".
There are no hard-and-fast rules for collision avoidance maneuvers. You basically have six options and their combinations, any of which will put you at a different point than you would be at the expected intercept (collision) point: climb, descend, turn left, turn right, speed up, slow down.
There was a study conducted by students at the University of Illinois at Urbana-Champaign, results available here, which might be helpful. The primary purpose of the study was to determine the usefulness of a computer traffic display in aiding the pilot to spot and avoid the traffic, but a secondary goal was to determine the most likely (and safest) collision avoidance maneuvers when presented with "intruders" on a collision course in each of 12 basic intercept paths (overtaking, crossing, or approaching, from the left or the right side, and climbing, level or descending). Among the lessons learned were:

Pilots (CFIs were used) were most likely to maneuver purely in the vertical to avoid traffic, moving opposite the vertical direction of the plane in sight and preferring to climb if the intruding traffic was holding altitude.
Despite the pilots' preference for the vertical, the maneuvers that cleared the "conflict" in the shortest time were in the horizontal plane, either turning opposite the plane's relative direction of travel to move behind, or slowing to let the traffic pass in front.
Pilots tended to do what was "easiest" at the time the conflict arose, especially if the intruder was sighted late (because the traffic didn't appear on the computer display; another of the variables they tested). Thus, single-axis maneuvers were most common (not counting the use of throttle to adjust power while performing a maneuver, such as cutting power to dive or increasing it to climb or turn).

Taking all this under advisement, the maneuver most likely to avoid a collision with another plane in otherwise clear skies is a level 30-45° turn in the direction of the intruding aircraft's tail, coupled with a reduction in airspeed if the intruder is on a crossing or approaching route (if he's coming up behind you, maintain airspeed). If the other pilot sees you and reacts at the same time, his most likely move will be a climb, which is fine; if he doesn't see you or react at all, you'll pass safely behind him at the same altitude hopefully avoiding his wake (if he's bigger than you).
However, there's some interesting game theory here. Any maneuver I tell you to make, except one, will keep you on a potential collision course if the other pilot reacts in the same way at the same time. As you supposed in your question, If you both climb, or dive, or speed up, or slow down, or try to turn behind each other, you'll crash (or at least get way too close for comfort). So, anything I tell you to do because it's unlikely the other pilot will do the same will be self-defeating, because eventually other pilots will do the same thing because it works.
The one move that won't result in a collision if mirrored is a 90° turn in the same direction as the intruder's movement across your vision. If he's on your left moving right, turn right 90°. If he's on your right, turn left. If the other pilot mirrors your maneuver, worst-case (an aircraft overtaking you directly from behind who turns the same way as you) you'll end up on parallel flight paths at whatever distance you first noticed each other. Best-case, you'll be heading away from each other and after a couple of minutes you can both reverse your turn and continue along your original heading.
But, this move is the worst thing you can do in several scenarios if the other plane holds its course. In high-offset crossing routes (close to 90°), turning away from the intruder will keep you out in front of him and probably too close for comfort, especially if he's faster than you (turning the crossing-route collision course into an overtaking collision).
Lastly, any formulaic maneuver we dream up in a two-plane scenario is going to break down when you add more planes, or restricted airspace, or weather. The maneuver may work in cross-country flight, but when dealing with merging Victor airways near a population center, there will be too many aircraft for any single avoidance maneuver to guarantee you'll get out of trouble without getting into more.
So, ultimately, your call.

There is another advantage in turning: You show the other pilot your wing instead of just the frontal view - this will make your plane much more visible. Granted, in some cases the other guy has his head down, but every bit helps.

Very thoughtful answer.

You use your PIC authority and best judgment to do whatever is safest. There are so many possible variables that a single answer isn't possible: aircraft types, closing speed, altitude, airspace, ATC instructions etc.
Obviously you can't do nothing, as you said, but unless you're a mind reader then you have no way to know what the other pilot will do. Or would do: it's possible that he hasn't seen you at all.
Having said that, if you have limited time and distance to react then your best bet is probably a vertical movement: aircraft at different altitudes can't collide, and if you're on different headings then you'll pass each other very quickly. Maintaining lateral separation at the same altitude is a lot more difficult, that's why formation flying needs special training.
Whether climbing or diving is best depends on the situation and you have to make that call. The only guidance I ever got from an instructor was about birds: he said their instinct if a collision is imminent is to dive, so you should climb to avoid them. But that won't help much with another aircraft :-)


text:
Can state police legally order a GA aircraft to immediately land?
In 1998, the Senate was considering adding language to the Coast Guard appropriations bill that would authorize State Police to issue orders that a GA aircraft must immediately land.
In that instance, the language was removed before the bill was passed due to serious feasibility issues with the logistics of such orders.
That information is 24 years old now, however - has any such power been codified in law anywhere else, since?

It's very difficult to prove a negative. Can you point to the potentially-relevant USC and CFR titles where you think such language may have been added? The bill referenced in your article would be a good starting point for research.

The bill in question was an appropriations bill and is long since stale. I'm not sure where to look in the USC/CFR for such a thing. Certainly 93.1 has nothing that suggests anyone but the pilot has authority to make lawful decisions about course and site of landing, which suggests that an LEO trying to order a plane to land is committing an act of aircraft piracy.  I'm assuming that I must be reading this wrong, but as you say, I can't prove the negative.

I suspect there might be circumstances where any police can order an aircraft to land, just like there are circumstances where police can order a car to pull over, even though they can't do that in the general case. For example, if they believe the plane is committing a crime.

@DJClayworth It's not clear that this is something they can do, actually. Because of the unique nature of aircraft operations, PICs are imbued, by law, with final authority as to the flight of the aircraft. Drivers are not so imbued anywhere I'm aware of.

Similar to my answer here (slightly different question so not a dupe). The short answer is no, local authorities have no jurisdiction over federal airspace. As noted here (r.e. drones but applies to aircraft as well)

Congress has provided the FAA with exclusive authority to regulate
aviation safety, the efficiency of the navigable airspace, and air
traffic control, among other things. State and local governments are
not permitted to regulate any type of aircraft operations, such as
flight paths or altitudes, or the navigable airspace.
...
Cities and municipalities are not permitted to have their own rules or
regulations governing the operation of aircraft. However, as
indicated, they may generally determine the location of aircraft
landing sites through their land use powers.

Also as codified here the United States has full control over its airspace (not up to local authorities).

Over here in Canada, yes. In the Canadian air regulations under 602.144 says
(1) No person shall give an interception signal or an instruction to land except
(a) a peace officer, an officer of a police authority or an officer of the Canadian Armed Forces acting within the scope of their duties;
We do not have such things as provincial laws or state laws, all the rules we have are straight from the federal government.


text:
What is the correct use of "REPORT LANDING ASSURED?"
Listening to BDL_TWR on my way to work and I heard tower request of what I presume to be a helicopter pilot: "report landing assured."
I'm an S2 VATSIM ATC and so I'm fairly familiar with the 7110.65Z, AIM, and FAR. From somewhere in all that I know that "landing assured" means "my engine could quit right now and I'd still safely make my intended landing surface."
But it occurred to me that I have no idea why/when/where it is incumbent on ATC to request that report from someone.  The internet seems to think that this is not official phraseology, but generally used when the aircraft is going to drop out of radio contact due to terrain where they are landing.  But I'd love a cite to an official source on proper/recommended use of such and can't find it.

It is not official phraseology and I don't think it's ever required. It's a technique or habit some controllers like.
Because BDL has a Class C service area, all aircraft are provided radar services. When an aircraft is being provided radar services, it must eventually be told one of two things:

"Radar service terminated" (7110.75 5–1–9), or
"Radar contact lost" (7110.55 5–3–7).

There are situations where neither one is necessary, enumerated at 5–1–9b. One such situation is:

An arriving VFR aircraft receiving radar service to a tower‐controlled airport within Class B airspace, Class C airspace, TRSA, or where basic radar service is provided has landed.

If a helicopter is landing elsewhere in the surface area, even if it is a defined heliport, then they are not landing at a "tower-controlled airport" and in theory they should be informed "radar contact lost" when they drop off the scope. The controller receiving a "landing assured" call gives them peace of mind that they don't need to go through a whole thing about radar contact being lost when, in fact, it is a normal and expected occurrence—and the pilot may never have been told "radar contact" in the first place, if they initially departed a ramp at the airport, for example, instead of entering the surface area after talking to Approach.
A non-radar tower controller might request a "landing assured" report for the same reason: controller peace of mind. No other reason.

"Landing assured" has no place in IFR operations and as far as I know, no place in VFR operations. It might be a holdover from MANY years ago passed along from trainer to trainee, but I never saw it in FAA Order JO7110.65.
If I was providing IFR separation between an aircraft executing an instrument approach at a non-towered airport and an aircraft trying to depart the same airport, the only way I could clear the departure is with a pilot reported down time or the pilot canceling IFR. "Landing assured" gets me nothing.


text:
Do aircraft using the push pull configuration always use the same engine?
I am currently doing research for a “white paper design” aircraft and I have always been interested in push pull aircraft as they seem to be rare and I wanted to see some challenges in making a very crude and college level aircraft. What I have been wondering is if aircraft in push pull configuration always use the same engine For both the pusher and the puller or is there a advantage in having it be offset where one engine does more of the “work then the other engine?

No. Just one example: Rutan Voyager.

Related, maybe dupe: https://aviation.stackexchange.com/questions/14261/are-all-the-engines-on-a-multi-engine-plane-the-same/14262#14262

Cessna made a few hundred Skymasters. Irreverent nickname "Suck and Blow."


text:
Comparison: e-aircraft vs. ground EV modes (car, coach, rail)
I'm looking for (and struggling to find) a comparison for any e-aircraft vs. ground EV modes (car, coach, rail) carrying an equivalent payload, an equivalent distance.
So basically, if you fly from London-Edinburgh in an e-aircraft with 4 passengers... how much electrical energy would that consume vs. driving a car with equivalent passengers and luggage?
so a kWh/kg-km comparison.
The plot in this article shows that on an emissions (proportional to fuel burn) basis for combustion engines that you are far better to drive (if multiple passengers), or take the coach or train vs. a domestic flight. https://www.bbc.co.uk/news/science-environment-49349566
I imagine that this relative efficiency comparison only gets worse when you switch from all combustion to all electric, as I understand aircraft are more heavily penalised by battery and electrical system volume/weight than ground transport... and the fact batteries don't burn-off mass as you dissipate energy as per jet fuel. So I'd expect the relative efficiency gap to widen.
Also e-aircraft (whether hydrogen- or battery-electric) are very limited on range/payload so for the same number of passengers it won't be able to fly as far: hence it will spend more journey time in take-off/climb than in cruise and this will make efficiency/kg-km worse again?
Would be very helpful understanding if this logic is flawed - and even more helpful if you have a legitimate quotable reference I can use!

First, design and field a fleet of all electric passenger aircraft. You can't run a comparison against something that does not yet exist.

Should the building of runways and roads be factored into the comparison?

@WPNSGuy agreed, although we're seeing a lot of CEOs of start-ups winning huge investment for e-aircraft which they claim will "decarbonise flying" (they won't any time soon as they can't compete on energy density vs. jet fuel) and claiming flying short hops in small e-aircraft is a green way to get around vs. the ground. So this latter claim is what I want to think through: short of waiting another decade to finally see the product spec.

@Peter Kampf ideally you want all emissiojs factored in but I'd be happy with just the vehicle operational emissions as a starting point. Rail and certainly road networks are already pretty well established across the planet.

Another problem with comparing electric aircraft to electric cars is that an aircraft will be using a large fraction of its maximum power at cruise, while a car uses only a small fraction at steady speeds on the level.  Almost all of the horsepower is used only for brief acceleration - the oft-cited 0-60 time.

@Green Sky Thinking - "although we're seeing a lot of CEOs of start-ups winning huge investment for e-aircraft " Yes...a lot of claims, PowerPoint presentations, Boardroom Bingo, sprinkled with a lot of handwavium. Until we see some butts in seats at 20k feet, going from London-Edinburgh, we can't do any real comparison. There is nothing published, because it does not yet exist.

@WPNSGuy: Though that begs the question of why anyone would fly commercial from London to Edinburgh, when train time is about 4 1/2 hours (from King's Cross).  My last experience of Heathrow suggests that getting there and through security often takes that long.

@jamesqf - Apparently, people do. EasyJet shows a schedule from Luton to EDI at 1 hr 15 mins. Add an hour or so at the departure. I just figured the OP used those places as known locations with airports. Could have been Washington to Boston, Or LAX to SFO. Or Paris-Berlin.

@WPNSGuy: Oh, I know people do fly, I just don't understand why they do.  Unless they have some secret card that lets them bypass all the security.  IIRC, the last time I went through Heathrow (back to US), it was over an hour to get there from St. Albans, via train & tube, another couple of hours for security & boarding, then time waiting to taxi...

Train wins, every single time. Zero induced drag.
Thanks to the magic of Timken roller bearings (in truth, plain bearings worked even better when rolling fast enough for the hydrodynamic layer to establish itself: roller bearings are only better at starting), the train's rolling resistance is effectively zero when comparing to any other mode of transportation.
And electrification is easy and 19th century tech.
Because the fixed guideway allows fixed electricity pickup*, which means you don't need to solve the battery problem.
That also means railway stock is dog simple, and does not need elaborate and difficult-to-manufacture battery packs involving exotic metals.  Just plain old steel and copper will suffice.  That's important because mining and refining exotic metals and making batteries has its own carbon cost.  Also, railcars last 50 years - longer than batteries.
In fact there is nothing on an electric train that can burn, except luggage, and furnishings if poorly chosen.  That in turn makes extended tunnel construction more feasible.
With rail, rolling resistance is basically nil, which makes the "weight penalty" very low.   Also, it does not need to flex (and spall) any rubber tires - another carbon-heavy consumable not needed.
Unfortunately, this efficiency has made rail inefficient.  Since there is little weight cost, little effort is made toward making trains light-weight.  Indeed, heaviness is desirable for accident survivability.  That mass has an accel/decel cost.  It is possible for smaller land vehicles to beat trains on kWh/person-km. (But your criteria is kWh/ton-km).
But the heaviness swings both ways: it can effortlessly move immense quantities of cargo.
Full disclosure: There is one more efficient means by kWh-ton-km: cargo ship. But those do not lend themselves to electrification because they venture so far from support.  Further, they have serious problems with speed, and require a transload: they cannot bring the cargo directly to the point of use, as trains can.
In a Mad Max no-oil scenario, it is certainly possible to run the ships on massive solar arrays.  But that is only going to slow them down much more than they already are.  Wind has millennia of prior art, but it doesn't scale well (partly due to square-cube law problems which also affect solar)... so it couldn't add a whole lot for large modern ships like Ever Given.

* Simple matter of suspending a steel catenary wire over the track, which suspends a 4/0 copper contact wire ($20/metre with the Cu shortage) with hangers set so the copper wire is level.  This is hung from poles and guyed side arms (simple stuff again).  For high speed operation, every km or so, it is tensioned by pulleys and weights.  Bonus points if you use 1750 ACSR steel cored aluminum wire as the catenary wire, which then doubles as low resistance feeder.

Actually, where practical, ocean ship beats train beats truck/lorry beats smaller automobile beats almost all airplanes for energy efficiency measured in payload distance per Joule (or any other measure that compared energy per payload mass and distance).

Conceded, but the human cost starts to pinch.  Take the Thomas W. lawson, crew of 18, call it 750 TEU, and best wind speed 16 kts.  Say half that in practice.  Shenzhen-Long Beach is over a month's sail.

Yeah if long-range cargo the best is clearly a ship. Thank you very much for this incredibly detailed overview of the efficiency of trains! Of course, the issue is that many places have limited rail infrastructure - so would be awesome to get a similar detailed description for planes vs. coaches vs. (multiple occupancy) cars.

For airplanes and cars, one approach might be to break it down to wattage per seat mile for each conveyance. Cars only need about 20-30 HP to cruise on the highway; say 22 kW.  An airplane needs about 120 kW (roughly 160 HP) to have decent performance for takeoff and climb with 4 adults and a bit of luggage, and might cruise using between 50 and 75% of that.
Say 50% power, at a high efficiency airspeed (fairly slow), so 60-70 kW for cruising from A to B, about 3 times what the car needs.  Maybe going 2 times faster than the car at its most efficient cruising speed, so the tripled power consumption is mitigated by the doubled speed, but the car still wins on a pure efficiency seat mile basis.
Of course this assumes you have a battery that achieves the power density of gasoline, which is some way off.  Currently you get about 1/3rd the range of gas, pound for pound, with current electric Li-ion battery power.

Consider what could be achieved though: an Eta glider weighs 8kN and has a sink rate of 0.4m/s at 100kph so 3200W, which compares favourably with, say, a 100cc motorcycle that achieves the same speed with around double the power.  Of course, the glider is converting potential energy in the form of altitude and doesn’t carry an additional energy source or propulsion system, and the infrastructure needed for Etas as personal transport would be nontrivial, but it goes to show that heavier-than air flight isn’t a priori less efficient than other methods.


text:
Are hot air balloons regulated by ATC or can they fly without reporting to ATC?
My question is: are hot air balloons required to report to ATC or are they allowed to fly on their own without reporting to ATC? I know that all commercial aircraft, no matter the size, must cooperate with Air Traffic Control (ATC) and report all their moves and request permission form ATC. However, I reasoned that hot air balloons would not have to do this because:

They don't require a runway and takeoff and landing of hot air balloons usually happen not in the airport but in remote areas that won't interfere with any other incoming traffic.
Hot air balloons don't have radar, so ATC is basically useless in tracking the flight should anything happen.

But I'm not sure if I'm correct. Do anyone know if hot air balloons have to report to ATC ? Or are they free to do anything they want? Or, by any chance, do they have their own traffic controller independent of ATC? Although this question may sound like a question I had posted earlier, it is not. I'm asking specifically for ATC-related regulations here, not general regulation differences between hot air balloons and jet aircraft.

all commercial aircraft, no matter the size, must cooperate ATC and report all their moves — not exactly... you're thinking of airline aircraft, and you're broadly correct about them but still not necessarily entirely correct. "Commercial aircraft" covers a lot more than just airliners though. Cropduster aircraft almost never talk to ATC. Photo-survey aircraft often talk to ATC when their missions require them to be in busy areas, but often don't if their missions don't require. Etc, etc.

Your premise that ATC controls all traffic is wrong, ATC controls traffic in... controlled airspace.

@randomhead  That's not even fully true about airliners.  See https://aviation.stackexchange.com/questions/26848/can-commercial-air-traffic-operate-from-uncontrolled-airport-airspace

First a word on terminology: ATC does not "regulate" aircraft. The FAA as a whole "regulates" aircraft (and aircraft operations) by publishing and enforcing regulations; FAA regulations are found in Title 14 of the Code of Federal Regulations.
Moving on...
The airspace above the United States, as in most countries, is divided up into "classes" which indicate which services are available from ATC. In order for ATC to provide the various services in the various classes of airspace, certain requirements are imposed on pilots operating in those areas. Nothing exempts hot-air balloons from following those requirements, which can include things like "communicate with ATC so they know who you are and what you're doing" and "have a working transponder so ATC can see you on their scope."
The vast majority of airspace across the USA is designated Class E. In this class of airspace, aircraft operating under Visual Flight Rules1 are not (generally speaking) required to contact ATC at all.
If a hot-air balloon pilot wants to enter non-Class E airspace they need to meet the requirements to enter that airspace, and they need to comply with any ATC instructions... to the extent that they are able to, given a balloon's maneuverability limitations. So the bottom line is that balloons are not exempted from any of the "ATC-reporting" requirements that other aircraft have follow.
On a related note, the right-of-way rules for when aircraft are not being sequenced by ATC state that balloons, being the least maneuverable, have the right-of-way "over any other category of aircraft."

1Meaning the pilots aviate by reference to the horizon, rather than instruments on their dashboard, and navigate by reference to the ground (or use dead reckoning), rather than following electronic guidance from a radio station. Pilots operating VFR are not permitted to enter clouds.

Thanks for the answer. This is exactly what I'm looking for. Although I originally didn't know airspace are divided into classes, and that most airspace in the USA are  class E. Your answer helps a lot.

The transponder isn't what allows the radar to "see" the aircraft.  It just provides that handy little label about which dot is which.


text:
What is the worst hot air balloon disaster in history in term of lives lost?
I've been wondering what's the worst hot air balloons disaster in history? I know there are many fatal crashes and accidents in aviation history, but most of them are airliners and other commercial jet aircraft. Hot air balloons had once been one and only way of going up into the sky. So there must've been some crashes and accidents that history just forgot about. Does anyone know a list of hot air balloon disaster ranked in casualties numbers?
Note: I'm looking for hot air balloon disasters, not rigid air ships disasters. I know about the famous Hindenburg disaster and the crashes of the ill-fated US Navy airships USS Akron, USS Macon, USS Shenandoah, and ZR-2 which never made its way back to the US. But I'm looking for actually hot air balloons that crashed with a lot of fatalities.

There's literally a list on Wikipedia...

@Chris why don't you put that link in an answer, copy the row with the Luxor accident. Would be an acceptable answer.

Whoever downvoted my question, please provide a suggestion or improvement in the comments so that I can know how to improve.

@AircraftEnthusiast007, Welcome to Aviation.Stackexchange! I'm not the downvoter, but a guess: it is the expectation here that you do your research before asking questions, and in this case, a google search of "hot air balloon accidents" would have yielded the Wikipedia page that Chris indicated.

There's a list on Wikipedia. The deadliest was in Egypt in 2013, with 19 deaths.


text:
What is the best procedure if the rudder falls off?
I've recently looked up American Airlines Flight 587, the second worst aircraft accident in U.S history. The main cause of the accident is the separation of the vertical stabilizer and rudder from the aircraft. This helped me understand that loss of a vertical stabilizer is not survivable. However, I have been wondering, is separation of only the rudder and not the whole vertical stabilizer survivable? By survivable, I mean to regain at least partial control of the aircraft, sufficient enough for a controlled, survivable emergency landing. If so, what procedures will maximize the chances of regaining control of the aircraft? Are there any experienced pilots here who can tell me? I will greatly appreciate any help. Thanks in advance!

Note: I'm not looking for speculation, explanation or description about the reasons of crash and course of event of American Airlines Flight 587. Rather, I'm asking whether or not a loss of rudder is survivable and if so, what procedures will increase the chances of survival.

Airliners don't need rudder to maneuver.

@CamilleGoudeseune *when both engines are operating and you're not landing with significant crosswind. Engine failure, particularly during full-thrust takeoff with light loads, is the dimensioning case for the vertical stabilizer and rudder.

@CamilleGoudeseune but for coordinated turns they do.

Mostly I just wanted to link to a related set of answers.  The "don't need rudder" summary of those can't catch all the exceptions, of course.

Avoid turns. Do not bank or roll. Continue to fly straight ahead to the accident site.

Aircraft can be flown without a rudder if the vertical stabilizer is still there. There are many pictures of aircraft landing safely after losing the rudder only, and still having the vertical stabilizer at least partially intact. To answer this for yourself, go fly in a Cessna "spam can" (152, 172) and don't touch the rudder pedals during the entire flight. Unless you do something really bizarre that would kill you with or without a rudder, the aircraft will fly, but your turns will be uncoordinated and you will not be able to execute a side slip to get down in a hurry, or crab the aircraft to compensate for a crosswind during landing.
American Airlines Flight 587 was uncontrollable because the entire vertical stabilizer with the rudder was ripped off. Both the rudder hinges and the bolts securing the stabilizer failed.

Thanks, your answer exactly is what I'm looking for! So the real culprit of American Airlines Flight 587 and similar accidents are because of the detachment of the vertical stabilizer, not rudder. I originally didn't knew that losing a rudder will not cause a crash. Thanks for telling me!


text:
What is the rationale behind requiring ATC to retire at age 56?
Commercial jet airliner pilots are required to retire before the age of 60 or 65, depending on region and regulations. The International Civil Aviation Organization (ICAO) set the retirement age at 60 for single pilot roles, and 65 for multi-pilot roles. Pilots basically are all allowed to continue to work until at least age 60, unless of known deficiencies, both medical or professional, that may hinder their ability to fly the aircraft safely. Otherwise, they may choose to retire at 60 to 65 years old. However, FAA regulates that all Air Traffic Controllers (ATC) must retire before age 56. ICAO did not set a global standard for the enforced retirement age of ATC, but most countries follow FAA's 56 rule, with a few variations. Why is there such a major difference between the required retirement age of pilots and ATC? Many sources I found stated that the ability to cope with the high-stress, fast-paced and multi-tasking working conditions and immense responsibility deteriorates with age1. However, each of these claims also applies to pilots. Pilots also have to deal with high-stress situations, sudden mishaps, or even emergencies. Although pilots can relax a bit when cruising, they need maximum concentration on the critical phases of the flight (i.e., taxi, takeoff, climb, decent, approach, and land). They also may have to deal with a large amount of overnight flights, and jet lag if they fly international routes. Why then, are ATC required to retire nearly a decade earlier than pilots? Is there another reason? I'll appreciate any help. Thanks in advance!

1: See what age must ATC retire

Anecdotally, it does seem like controllers' abilities start declining as they approach 56. I've seen it with a couple of coworkers and people on Reddit mention it somewhat often. Also note that Federal LEOs and firefighters also have early retirement.

If there is not an early hard limit then you end up with some sort of tribunal process for older controllers that effectively fires them for being 'senile' - which is not something anybody wants to be involved with I suspect, especially a government agency. Sometimes an unfair rule evenly applied is better than a fair rule erratically (and probably expensively) applied.

Any comment from downvoter?

Pilots can relax a bit during the flight/work hours.  ATC is full stress from clocking in to clocking out.  Responsible for keeping many aircraft safe for hours and cannot make a single mistake.   Not a job I would want.  56 is probably pushing it.

As noted in other answers but salient: ATCs handle multiple - sometimes dozens - of aircraft simultaneously while pilots operate a single aircraft.  A disastrous error by a pilot can kill hundreds but even in a mid-air between two fully loaded 747s, there's two pilots involved and responsibility is distributed.  A similarly severe ATC error can have double the consequences, or more.
Pilots operate machines, while ATCs do their best to influence (thankfully quite cooperative) human behavior. At the end of the day, the NAS is chaotic in ways that flight just isn't.  Pilots receive direct, observable feedback to their command/control inputs to aircraft operating normally.  ATC, especially in TRACON and En-Route positions, receive delayed, probabilistic feedback for the actions they take.  The anticipatory tension experienced by ATCs is thus higher.  Pilots do have more skin in the game - they're on board their craft - but they have more immediate control over what situations their craft experiences as well.
ATCs, consequently, suffer elevated health consequences compared to pilots.
These include:
From this 1978 study - Hypertension (substantially elevated risk), respiratory illness (not super conclusive because of wide variance in diagnostic criteria), peptic ulcers
From this earlier study - Hypertension, Peptic Ulcers, Diabetes
From a 2015 study - Poor sleep quality, poor quality of life scores, concentration issues, higher body fat percentages with all comorbidities that implies.
The selection of age 56 specifically was not scientifically determined but is consistent with the maximum hiring age of 30 allowing 25 years of service, sufficient to justify pension benefits and other retirement perks while still being earlier enough in a retired controller's life as to allow a second career in less stressful work.
It's important to acknowledge that studies since the 70s, when this retirement age was laid down in law, don't find the evidence as compelling as was understood to be the case at that time.  Nor, however, is it dispositive.  More modern evidence suggests that the health impacts of ATC work have as much to do with the work culture, structure of shifts, and staffing shortages as anything else - i.e. it's not the work itself, but how it's being performed.
Evidence does exist, as of 2005 anyway, that controller performance suffers more variability as a function of age in ATCs than in other types of work - and certainly attention to detail and concentration issues - which also correlate with age - are especially deleterious to the work ATCs do.
None of this is perfect, but the studies from the 1970s did use airmen as a comparison/control group.
TL;DR - Pilots and ATCs suffer different kinds of stress which acts on the body and mind in different ways. ATCs are required to process far more discrete information at a constant rate and have far less immediate and direct control over the systems they operate.  At the time the mandatory retirement age was instituted, best available scientific research suggested that ATCs burned out more quickly and thus there was merit to making them eligible for retirement benefits earlier and safety reasons to force them to take it.  Our understanding of the situation is evolving, but the law is always slower to change than our knowledge.

In the 1970's (sorry, couldn't find the exact year) the ATC union, the Professional Air Traffic Controller Organization (PATCO) lobbied for an earlier retirement for ATC personnel. PATCO cited the stress of the job and reduced abilities as controllers aged. A law was passed that created a mandatory retirement for controllers at age 56, and a maximum age of 30 for being hired.
Under the new law, controllers and first-line supervisors could retire at age 50 with 20 years of "good time" (actively controlling air traffic, staff time didn't count) or with 25 years good time at any age. All other jobs in the FAA used the regular Civil Service Retirement System age requirements. The maximum age to be hired (30) ensured that controllers were able to reach retirement eligibility once they turned 56.
Controllers hired before the change in the law had a minimum age (18) but no maximum, so they were exempt from the mandatory retirement at age 56. I worked with many when I started my career. For the most part, these controllers retired (if they were eligible) around their mid fifties anyway.
On good weather days, controlling traffic was sometimes moderately stressful during a typical shift. On bad weather days, it could be really tough. As controllers age, the bad days start to add up, and combined with shift-work that featured eve-eve-day-day-mid shifts in a five-day period, it really takes its toll over the long run, not only on your mental acuity but your overall health as well.

Also, sorry if I'm a bit unknowledgeable, but what does "eve-eve-day-day-mid" shifts mean? Does it stand for "evening-evening-afternoon-afternoon-midday" shifts? Or is it "evening-evening-morning-morning-midnight" shifts instead? Which one, or neither? Thanks in advance for any explanations!

@Air: the second one, and it's a terrible horrible no-good very-bad schedule for one's sleep health. The FAA is just now rolling out new rules that will in effect (although not in so many words) prohibit this "rattler" schedule.

Decades ago, unions in plants often followed the rotating shift schedule - one week on days, one week on evenings, and one week on nights. That meant everyone did the same schedule and there was no pay differentials. Research showed that this was absolutely horrible for both individual health and safety on the job.

@Aircraft Enthusiast 007 A typical workweek was a rotation of 4PM-12, 2PM-10, 8AM-4, 6AM-2, and 11PM-7, so you were always coming in earlier each day. This compressed your workweek but maximized your weekend (get off at 7AM on your Friday and don't come back until 4PM on your Monday). It wasn't worked this way at every facility, but for facilities that worked mids (some close overnight) it was the prevalent shift rotation. It is really tough on your body over the long haul.

I took a RJ jet type course as a newbie at age 52. It was known as the "fire hose". I discovered that an old timer's physical skills come easy (these jets are quite easy to fly as airplanes, once you adapt to the speed/mass aspect), but the mental part was brutal. And a type course is 80% mental. much of it memorization and recall under intense stress. I started to understand the early retirement requirement for ATC.

The basic rationale dating back to the 70's is, simply put, that ATC personnel handle a constant flow of many planes, while pilots only manage one plane.
From "Review of the Scientific Basis for the Mandatory Separation of an Air  Traffic Control Specialist at Age 56", page 2 (10th actual page) (link to pdf)

At this point, Mr. Francke identified several reports
“proving” that the business of air traffic control was
highly stressful. He first contrasted the description of
the pilot occupation as “hours of boredom intermixed
with moments of sheer terror” to a description of the
ATCS occupation:

The controller has no such hours of boredom; he must
frequently work for 8 hours at a stretch without rest
periods and gulping his lunch at his position. Because
of shortages of personnel, many of them have been on
6-day weeks for several years. This situation is further
worsened by the fact that air traffic control is a 3 shift
per day, 7-day a week operation, and each controller
must take his turn standing midwatches. This is usually
not too onerous on the younger man, but older men
usually have difficulty in changing the rhythm of their
life, and in sleeping during the daytime in the periods
that they are on midwatches (Hearings, p. 98).

This comparison may be outdated and a little exaggerated, and depends greatly on where the controller is stationed or what kind of routes the pilot flies. But one might very well argue, that an aircraft is a more stable system to handle than, say, a CTA is.

And the only time the ATC deals with planes is during the most dangerous part of the flight. While pilots spend significantly less time under stressful situations.